When preparing a person's teeth for installation of a bridge, crown, inlay or pin restoration, it is often necessary to drill parallel holes and/or grind parallel surfaces on the axial surfaces of the patient's teeth. The handpiece guides presently available for such operations are generally bulky, cumbersome, inaccurate and are impractical. Moreover, most prior guides have lacked the desired maneuverability and versatility which is necessary if the dentist is to prepare the teeth with controlled parallelism and taper and a minimum expenditure of time and effort.
Prior art devices have required a massive array of interconnecting arms and pivot members and are thus complicated in design and cumbersome in operation to the point of impracticality.
Typically, the devices have a mounting plate which is to be affixed to the teeth laterally disposed from the tooth to be operated on, or a base plate cast from acrylic or other material and positioned in the mouth. At least two prior art devices have provided for pivotal adjustment of the cutting axis relative to the mounting plate, but such adjustment devices do not provide for easy and relatively acute angle pivotal adjustment of the cutting axis relative to the mounting plate.
Further, some of the prior art devices have not provided for an adequate means to firmly hold a handpiece head to keep the cutting axis from shifting once the desired orientation of the cutting axis is achieved.
Still further, the prior art devices have failed to provide for freedom of rotation and essential vertical movement of an instrument when an operator places unwanted, but unavoidable, lateral or rotational forces on the guide while directing the handpiece in the preparation of teeth.
Still another disadvantage of the prior art devices has been that they have not provided a means to easily and simply disassemble part of the device for removal from the patient's mouth so that the remaining portion of the device retained in the patient's mouth is kept to a minimum and is relatively small in size so that the patient can partially close his jaw to rinse, speak etc. and allow for off-axial preparation of the teeth without disturbing the anchorage of the instrument.